This invention relates to intraocular lenses (IOLs). More particularly, the invention relates to foldable IOLs having highly pliable optics and relatively less flexible haptics that may be placed in either the anterior or posterior chamber of the eye through very small incisions.
Intraocular lenses (IOLs) are commonly used to modify or enhance vision. IOLs can be placed at various positions or locations within the eye. For example, IOLs can be placed in the anterior chamber (AC) of the eye, that is, the region of the eye posterior of the cornea and anterior of the iris. Alternatively, a posterior chamber (PC) IOL is implanted behind the iris, typically in the capsular bag from which the natural lens has been removed.
IOLs advantageously have been foldable for insertion through small incisions (less than about 6 mm), particularly for insertion in the capsular bags in the posterior chamber of the eye. IOLs may generally be classed by material. Hard or rigid IOLs are distinguished from soft IOLs that may be folded to facilitate implantation through a small incision in the cornea (and capsular bag for posterior lenses).
A typical IOL has a disk-shaped optic with 2 to 4 fixation members extending outward therefrom. For purpose of orientation, 3:00, 6:00, 9:00, and 12:00 positions around the optic may be defined, thus locating perpendicular 3/9 o""clock and 6/12 o""clock axes. As a matter of convention, a three-piece IOL (i.e., an optic and 2 haptics) is oriented along the 6/12 o""clock axis such that the haptics project outward generally along that axis (so that the haptics are often opposite mirror images of one another across the 3/9 o""clock axis). Four- or five-piece IOLs are oriented likewise. Such IOLs are normally introduced through the incision using a Bartell-style injector, for example as described in Bartell U.S. Pat. No. 4,681,102, the disclosure of which is hereby incorporated herein in its entirety by reference.
A Bartell-style injector folds the optic along the 6/12 o""clock axis, thus defining leading and trailing haptics. The profile of the haptics along the 3/9 o""clock axis is less than about 6 mm so as to fit through small incisions. This means that either a single haptic has a length dimension of less than about 6 mm or that the outermost portions of two haptics are spaced apart less than about 6 mm. Unfortunately, this size limitation reduces the implanted stability of the IOL, increases forces transmitted to the optic which may increase optic displacement, hinders symmetric placement of the IOL within the capsular bag in PC implants, and potentially increase the severity and occurrence of pupil ovalization in anterior chamber implants.
IOLs may be oversized relative to the peripheral anatomical structure and flexible in the plane of the IOL such that they are placed in compression when implanted. Both soft and rigid IOLs exert retention forces on their outer ends that are desirable so that the lens is held in place or centered, otherwise a loose fit might cause vision and other problems. However, a balance must be observed between sufficient compression for a good fit and excessive compression that adversely affects the IOL performance. For example, problems of corneal touch and further endothelial cell loss may arise in some current anterior chamber IOLs, whether formed of soft or rigid materials, which may deflect along the optical axis even with only a small magnitude of compressive fit.
A common technique for placement of an intraocular lens in the anterior chamber is within the iridio-corneal angle, in a so-called xe2x80x9cangle-supportedxe2x80x9d configuration. A number of non-foldable angle-supported anterior chamber intraocular lenses are fabricated from rigid materials, such as polymethyl methacrylate (PMMA). These rigid anterior chamber intraocular lenses are typically based upon a Kelman design of thin, flexible haptics or fixation members with 3 or 4 footplates or pods. Unfortunately, some designs provide less than desirable foldability, or else have minimal compressive retention forces that permits unwanted intraocular lens movement.
It would be advantageous to provide foldable IOLs which provide one or more of the following: reduced incidences of one or more known complications caused by prior anterior chamber IOLs, effective and safe folding for insertion in the eye, safe and effective fit to a range of sizes of eyes, a minimum of translational movement of the optic of the IOL along the optical axis from the compressive fit in the eye, and an otherwise stable optic to avoid unwanted movement.
New lOLs for implantation in eyes have been discovered. The present IOLs are sized and structured to reduce the incidence of one or more known complications in the eye caused by prior IOLs.
The present invention provides a foldable intraocular lens for implantation in the eye, comprising an optic centered on an optical axis and made of a highly pliable material, the optic having a generally circular periphery and an integral flange extending radially outward therefrom. A cantilevered arm extends radially outward from the periphery of the optic and is made of a material that is flexible but more rigid than the material of the optic, the arm being attached to the optic. A pair of fixation members integral with the cantilevered arm support the optic centered on the optical axis of the eye. Each fixation member has a proximal end at the outer end of the cantilevered arm, a distal end, and a flex portion intermediate the proximal and distal ends. The flex portions extend generally away from one another adjacent to their respective proximal ends on diametrically-opposed sides of the optic.
Desirably, the material of the optic is selected from the group consisting of, silicone, hydrophilic acrylic, and hydrophobic acrylic. The material of the cantilevered arm and fixation members may be selected from the group consisting of PMMA, and polyether sulfone. If the optic is a meniscus type of optic it desirably has a center thickness of less than about 0.5 mm. The fixation members preferably have a thickness and flexibility that enables them to be folded inward toward one another so as to overlap the optic and present a smaller insertion profile than the diameter of the optic.
The cantilevered arm may include a main elongate portion and a paddle that overlaps one side of the flange, and the intraocular lens further includes a coupling member separate from the optic and cantilevered arm. The coupling member preferably includes a portion that overlaps the flange on the side opposite the paddle, and a stepped edge that has approximately the same thickness as the flange. The coupling member and paddle sandwich the flange therebetween and the stepped edge of the coupling member directly contacts the cantilevered arm, wherein the cantilevered arm, flange, and coupling member define an attachment assembly that is bonded together. The attachment assembly is preferably bonded together using a method selected from the group consisting of heat staking, laser welding,and ultrasonic welding.
The flex portions of each fixation member may extend generally away from one another adjacent to their respective proximal ends and then turn about 90 degrees to form substantial U-shapes that have lengths greater than the diameter of the optic, the U-shapes being oriented generally in parallel on diametrically-opposed sides of the optic. When the lens is adapted for anterior chamber implantation, each flex portion of each fixation member includes a pair of spaced apart pods for contacting the iridio-corneal angle in the anterior chamber. Each pair of pods is desirably spaced apart at least seven mm. When the lens is adapted for anterior chamber implantation, each flex portion of each fixation member includes a pair of spaced apart pods for contacting the iridio-corneal angle in the anterior chamber. The four pods are desirably arranged on the flex portions so that upon inward compression of between about 0.5-1.5 mm, they form a square in the iridio-corneal angle so as to reduce the chance of pupil ovalization.
A further aspect of the present invention is a foldable intraocular lens for implantation in the eye, comprising an optic centered on an optical axis and made of a highly pliable material, the optic having a generally circular periphery. A cantilevered arm extends radially outward from the optic periphery and is made of a material that is flexible but more rigid than the material of the optic. The arm is attached to the optic periphery using a method selected from the group consisting of heat staking, laser welding, and ultrasonic welding. A pair of fixation members integral with the cantilevered arm support the optic centered on the optical axis of the eye. Each fixation member has a proximal end at the outer end of the cantilevered arm, a distal end, and a flex portion intermediate the proximal and distal ends, the flex portions being oriented generally in parallel on diametrically-opposed sides of the optic. Desirably, the fixation members have a thickness and flexibility that enables them to be folded inward toward one another so as to overlap the optic and present a smaller insertion profile than the diameter of the optic.
In a still further aspect, a foldable intraocular lens for implantation in the eye is provided. The intraocular lens includes an optic centered on an optical axis and made of a highly pliable material, the optic having a generally circular periphery and an integral flange extending radially outward therefrom. A fixation member supports the optic centered on the optical axis of the eye, the fixation member having a proximal end, a distal end, and a flex portion intermediate the proximal and distal ends, the proximal end having an arm extending toward the optic and a paddle on the end thereof that overlaps the flange and is connected thereto. A coupling member separate from the optic and fixation member includes a portion that overlaps the flange, and a stepped edge that has approximately the same thickness as the flange. The coupling member and paddle sandwich the flange therebetween and the stepped edge of the coupling member directly contacts the arm, wherein the arm, flange, and coupling member define an attachment assembly, the assembly being bonded together.
The fixation member, arm and paddle may being integrally formed of a material that is flexible but more rigid than the material of the optic. Desirably, the material of the arm and fixation members is selected from the group consisting of PMMA and polyether sulfone. The attachment assembly is preferably bonded together using a method selected from the group consisting of, heat staking, laser welding, and ultrasonic welding. The flange may include an aperture and the coupling member has a projection that fits through the aperture and contacts the paddle on the other side of the flange. Preferably, the fixation member arm and paddle and coupling member are made of the same material, in the attachment assembly is bonded together using heat such that the portions in direct contact fuse together.
In accordance with the present invention, a method of folding and inserting an intraocular lens in an eye comprises:
providing an intraocular lens having:
an optic centered on an optical axis and made of a highly pliable material, the optic having a generally circular periphery;
a cantilevered arm extending radially outward from the optic periphery made of a material that is flexible but more rigid than the material of the optic, the arm being bonded to the optic periphery; and
a pair of fixation members integral with the cantilevered arm for supporting the optic centered on the optical axis of the eye, each fixation member having a proximal end at the outer end of the cantilevered arm, a distal end, and a flex portion intermediate the proximal and distal ends, the flex portions being oriented generally in parallel on diametrically-opposed sides of the optic;
flexing both of the fixation members toward one another so that they overlap within the diameter of the optic and define an insertion profile of less than about 5 mm; and
passing the intraocular lens with the fixation members overlapping one another through an incision in the cornea of 5 mm or less without otherwise manipulating the optic into a fold.
The flex portions are desirably oriented generally in parallel on diametrically-opposed sides of the optic, and the flex portions of each fixation member extend generally away from one another adjacent to their respective proximal ends and then turn about 90 degrees to form substantial U-shapes that have lengths greater than the diameter of the optic, the U-shapes being oriented generally in parallel on diametrically-opposed sides of the optic and having inner arms and outer arms. The method of the present invention thus includes flexing both of the fixation members toward one another so that the outer arms overlap the diameter of the optic.
These and other aspects and advantages of the present invention will become apparent in the following detailed description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.